This invention relates to electric power distribution systems, and more particularly, to interfaces between overhead electrical distribution lines and electrical equipment.
Present interfaces employ poles or towers to terminate overhead lines or conductors. Electrical cables, supported by these poles or towers, are used to connect the overhead lines with associated electrical equipment such as transformers or switchgear. In smaller installations this associated equipment may be located on the pole or tower itself, but in larger installations such equipment is usually located on ground level.
With the use of such prior art interface devices, much of the equipment such as bus bars, disconnects, fuses, etc. is open to the elements and a fence around such an installation is required to prevent people from coming into contact with objects such as conductors, etc. having an electric potential. When towers of the type that employ metal lattice work are used, a fence is commonly required to discourage people from climbing the towers.
An additional drawback to the use of towers is the fact that they can be costly to install, they generally are not very aesthetic, and they frequently occupy considerable space.
Also known in the electrical art is the use of metalclad bus duct and isolated phase bus duct to interconnect pieces of electrical equipment. Briefly stated, isolated phase bus duct comprises a conductor, a generally cylindrically-shaped metal enclosure, or duct, at ground potential surrounding the conductor, and means insulating the conductor from the enclosure. One such bus duct is used for each phase of an electrical system, thereby isolating the phases from each other, and thus the name isolated phase bus duct. Metal-clad bus duct is somewhat similar in that it also has a generally cylindrically-shaped grounded metal enclosure, but it differs in that it has three conductors, insulated from each other, contained inside the single metal enclosure, one conductor for each phase. In a typical installation, the bus duct is supported at various points along its length, as is well known in the prior art.
In the prior art, the overhead lines of a power distribution system are terminated at towers (or poles) and flexible cables or conductors are used to connect the overhead lines to the associated electrical equipment. This associated electrical equipment is then connected to other electrical equipment by various means, including the aforementioned isolated phase bus duct and the metal-clad bus duct.
The present invention obviates the use of separate towers or poles as hereinbefore described, by employing the aforementioned isolated phase or metal-clad bus duct to provide not only the electrically conductive path between the overhead lines and the associated electrical equipment, but also the mechanical strength necessary in order to eliminate the towers and poles of the prior art.